function PE = GetParametersOfEarth( )
    PE.a=6378137.0;% 赤道半径 地球长半轴长度/m
    PE.r=6371008.7714;% 平均半径 average radius of earth/m
    PE.e1=0.0066943800229;% first eccentricity ratio of earth/m
    PE.e2=0.00673949677548;% second eccentricity ratio of earth/m
    PE.rotation=7.292115E-5;% rotation of earth
    PE.c=3.3528106E-3;% compression of earth
    PE.pgm=3.986004418E+14;% product of gravitational const & mass of earth
    PE.j2=1.082629832258E-3;% J2地球引力的一阶扁率系数oblateness
    PE.g0=9.80665;% gravity acceleration of sea level
end
% 地球是一个两极略扁，中部略鼓的椭球，其赤道半径为6378公里，平均半径为6371公里。
